Circuit maker target
![circuit maker target circuit maker target](http://2.bp.blogspot.com/-m5ODCIpSxI0/UE_DUMG_ATI/AAAAAAAAN3c/n2bAL825chs/s400/cricket_expression.jpeg)
When C has charged to the peak point voltage V P of the UJT, the UJT is turned on, decreasing greatly the effective resistance R B1 between the emitter and base1. The voltage across its the volatge V E applied to the emitter of UJT. When switch S is first closed, applying power to the circuit, capacitor C starts charging exponentially through R to the applied volatage V. The UJT relaxation as a relaxation oscillator is shown in Figure 3, generates a voltage waveform V B1(Figure 3), which can be applied as a triggering pulse to an SCR gate to turn on the SCR.
![circuit maker target circuit maker target](http://photos1.blogger.com/blogger/5857/3548/1600/pic7.jpg)
Since the emitter base junction voltage V BE for a fixed current decreases by about 2 mv/c o, therefore the ramp speed increases with the temperature. The draw back of constant current ramp circuit is that it makes the sweep rate as a function of temperature. If the emitter to base voltage V EB remains constant with time after the switch S is opened, then the collector current will be a constant whose normal value, The value of emitter current is given by the relation. This characteristics may be used to generate a quite linear ramp by causing a constant current to flow into a capacitor.
![circuit maker target circuit maker target](https://images.icemakeri.com/l-m/2a0836-02-ice-maker-control-circuit-board-v-2991837931.jpg)
We know that except for very small value of collector to base voltage, teh collector current of a transistor in the common base configuration is very nearly constant, when the emitter current is held fixed.
#Circuit maker target generator
Constant Current Ramp Generator Figure 2: Constant Current Ramp Generatorįigure 2 shows a circuit to generate a ramp using constant current from a common base transistor. At the end of time T S, the capacitor discharges and the voltage is again zero. It may be observed that the transistor switch is OFF only for the gating time (T S). This equation represents an approximately linear waveform. Then taking only the first term of the power series, the output voltage.
#Circuit maker target series
If t / R CC << 1, then above relation may be expanded into a power series in t / R CC. The charging curve ignoring V CE (sat) is given by the relation. As a result of this, the capacitor voltage rises to a target value V CC with a time constant R CC. a negative pulse is applied the transistor turns OFF. Actually its value is equal to V CE (sat). Initially the transistor is biased ON and operates in the saturation region. Figure 1: (a) RC Ramp Generator (b) Input & Outut Waveforms It may be obtained from a Monostable multivibrator (i.e. This circuit requires a gating waveform V i as shown in Figure 1(b). RC Ramp Generatorįigure 1 shows the basic circuit of RC ramp generator. In this method a constant current is approximated by maintaining nearly constant voltage across a fixed resistor in series with a capacitor. In this method a capacitor is charged linearly from a constraint current source. In this method a capacitor is charged through a resistor to a voltage which is small in comparison with the supply voltage. Ramp Generation MethodsĪlthough there are a number of methods of ramp generation, yet the following are important from the topic point of view. This topic consider the circuits employed in the generation of voltage and current sweeps. Linear current ramp generator are extensively used in television deflection systems. Linear ramp generators are also known as sweep generators, from basic building blocks of cathode ray oscilloscope and analog to digital converters. Voltage and current linear ramp generator find wide application in instrumentation and communication systems.